287 
0. Hay Murray 
the lancets are withdrawn. There is no trace whatever of palps belong¬ 
ing to the maxillae. The-two mandibles unite to form an organ with a 
sharp piercing point, and a hollow interior which serves as a sucking 
tube. When at rest in the proboscis groove, the mandibles project 
rather further than the maxillae as shown in the sketch (Fig. 8) of the 
enlarged tip of the rostrum. 
The mandibles are not toothed, and evidently in the process of 
feeding they first pierce the skin, and afterwards the maxillae, with 
their barbs, further lacerate the tissues and start the flow of blood 
which is sucked up by the mandibular tube. A section across the stylets 
and rostrum shows the two mandibles united together with a maxilla 
on either side (Fig. 10). The same arrangement continues to the tip, 
except that the maxillae become relatively smaller as they recede from 
the base. All four stylets have cavities in their substance quite apart 
from that which they unitedly form, these being prolongations of the 
body cavity. 
Landois’ statement that each of the components of the stylet tube 
forms a quarter circle, must be put down as an error, due to his lack of 
suitable appliances for section-making. 
In a mandibulate insect, such as a beetle, the mouth parts (the 
mandibles and maxillae) are outside the mouth proper, so that mastica¬ 
tion takes place before the food enters the mouth. In the bed bug it 
would at first appear as if these parts were inside the mouth and not 
in their normal position, but sections of the head show that they work 
in cavities which communicate directly with the outer air. These 
cavities open to the exterior at the base of the rostrum, and are con¬ 
tinued until they join up with the hollow which becomes the groove 
in the rostrum. The sketches show what is meant (Figs. 14 and 15), 
the longitudinal one being taken a little to the side of the middle line, 
while the transverse one is taken almost where the lancets have their 
muscle attachments. This point is just beyond where the pump muscles 
end, and is therefore about the level of the brain. 
The sketch (Fig. 17) shows a dissection of the head and the relative 
position of the pharyngeal pump (of which more hereafter) and the mouth 
parts. The lancets unite, and the tube thus formed from the maxillae 
and mandibles passes through a chitin-surrounded orifice, in the front 
of the crop, likened very appropriately by Landois to the thickened 
edge round the neck of a bottle (Figs. 12 and 17). This orifice is under 
the prominence from whose distal end the labrum arises, and is fastened 
to the under side of the prominence at that point. Thus the stylet 
